Measuring and monitoring emissions of nitrogen oxides from passenger cars

- a 1200 vehicle case study

Jane Thomas

12 October 2016

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• Nitrogen oxide emissions are on average four times the legal limits in real-world driving

• Real-world MPG for model year 2016 vehicles is on average 29% below official figures

• Carbon dioxide emissions are 41% above official levels

• Performance differs significantly between models homologated to same standard

• The new regulations for MPG, CO2 and NOx will improve but not solve the problem

• After 8 years of work at UN and EU, that will disappoint the market

• The need for an independent, real-world standard is greater than ever

The issue

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• Founded in 2011

• Headquartered in UK, with operations in London, Los Angeles and Stuttgart

• Specialist in PEMS testing and data analysis

• 1200+ vehicles tested

• Largest commercially available database of real-world emissions data

• Works with OEMs, Tier 1/2 suppliers, fuel and chemical companies, regulators, consultancies, consumer media

Emissions Analytics’ credentials

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• Rolling in-service surveillance programme of production vehicles

• Target to test 500+ vehicles per year

• To complement type approval

• Air quality, greenhouse gases, fuel economy

• Independent, making data available to all

• Top-level ratings for sales and marketing

• Benchmark rankings

• Deep-dive analysis

Objectives

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Equipment

• SEMTECH-DS and -LDV

• Portable Emissions Measurement System connects to tailpipe

• Captures emissions for CO2, CO, NO, NO2, total hydrocarbons

• At 1 Hertz

• Air temperature, pressure, humidity

• GPS for speed and altitude

• Engine data via CANBUS

• Fuel economy derived via carbon balance

• Weight addition 100 kg

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How PEMS works

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• Reproducibility must be weighed against authenticity

• Aim to drive same cycle identically each time

• Control what you can – driver, vehicle conditioning, driving style

• Careful QA of data

• Normalise out as much of remaining variability as possible

Approximate to laboratory

Use better economics of testing to test more cars

Trading slight deterioration in precision for greater sample size

Greater overall confidence

Emissions Analytics concept

REGULATORY TRENDS

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Test cycles

New EuropeanDriving Cycle

(NEDC)

World Light Duty Transient Cycle

(WLTC)

Real Driving Emissions (RDE)

EmissionsAnalytics

Measurements MPG, CO2, CO, NOx MPG, CO2, CO, NOx NOx

MPG, CO2, CO, NOx, NO, NO2

Cycle Defined speed trace Defined speed traceUndefined with

aggregate and dynamic constraints

Defined route

Test location Laboratory Laboratory On road with PEMS On road with PEMS

Conduct By OEM By OEM By OEM Independent

Normalisation None NoneCO2 windows or

power binningBased on dynamic

characteristics

Average speed (mph) 21 29 Varies 28

Average acceleration (mph/s)

1.1 1.0 Varies 1.5

Average gradient (m/s) 0.0 0.0 Varies 0.8

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Tightening regulatory levels

2016 2017 2019 2021

Gasoline

CO2 (g/km) – fleet average

130 on NEDC 130 on NEDC 130 on NEDC 95 on NEDC

NOx (g/km) – vehicle level

0.060 on NEDC0.126 on RDE for new types

0.126 on RDEfor all cars

0.090 on RDEFor all cars

CO (g/km) – vehicle level

1.000 on NEDC 1.000 on WLTC 1.000 on WLTC 1.000 on WLTC

Diesel

CO2 (g/km) – fleet average

130 on NEDC 130 on NEDC 130 on NEDC 95 on NEDC

NOx (g/km) – vehicle level

0.080 on NEDC0.168 on RDE for new types

0.168 on RDEfor all cars

0.120 on RDEFor all cars

CO (g/km) – vehicle level

0.500 on NEDC 0.500 on WLTC 0.500 on WLTC 0.500 on WLTC

VEHICLE PERFORMANCE TRENDS

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• Rolling 12-month average of exceedance factor in blue

• Step-change technology launched Q2 to Q3 2014

• No further reduction in Conformity Factor since then

• Average CF dipped to 2.7 in 2014, but risen to 3.5 since then

NOx Conformity Factor

0.00

5.00

10.00

15.00

20.00

25.00

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Co

nfo

rmit

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acto

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Test date

Euro 5/6 NOx diesel Conformity Factor over time

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• German manufacturers leading introduction of Euro 6 vehicles

• And offer the cleanest

• US manufacturers slow to bring Euro 6 vehicles to market

• Japanese very consistent around market average conformity factor

NOx by country

0.00

5.00

10.00

15.00

20.00

25.00

18/10/2012 06/05/2013 22/11/2013 10/06/2014 27/12/2014 15/07/2015 31/01/2016

Co

nfo

rmit

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acto

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Test date

Euro 6 diesel NOx Conformity Factor by country

Germany Japan Other US

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• Earliest Euro 6 vehicles were LNT and EGR-only, but LNT quickly became dominant technology

• More recent switch to SCR

• Nevertheless, good performance achieved by many LNT systems

• Similarly wide spread of performance between LNT and SCR

NOx by after-treatment type

0.00

5.00

10.00

15.00

20.00

25.00

18/10/2012 06/05/2013 22/11/2013 10/06/2014 27/12/2014 15/07/2015 31/01/2016

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Test date

Euro 6 diesel NOx Conformity Factor by after-treatment type

Exhaust Gas Recirculation (EGR)-only Lean NOx trap (LNT) Selective Catalytic Reduction (SCR)

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• Conformity factor initially 2.1 – 168 mg/km

• Further increased by exclusions due to boundary conditions

• PEMS test-to-test variability of 30%, so OEMs will need to target ~129 mg/km to avoid getting caught by in-service surveillance

• 1 in 5 vehicles already meet this

Will Real Driving Emissions help?

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

14/09/2011 01/04/2012 18/10/2012 06/05/2013 22/11/2013 10/06/2014 27/12/2014 15/07/2015 31/01/2016

Co

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Test date

Euro 5 Euro 6

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• Historically, CF ~4 and rising real-world fuel economy

• As many Euro 6 vehicles hit the market in 2014, CF began to fall

• In 2015, real-world fuel economy fell significantly for first time

• Effect particularly of LNT and EGR?

Knock-on effect on fuel economy

2.5

3.0

3.5

4.0

4.5

5.0

44.0

45.0

46.0

47.0

48.0

49.0

50.0

2012 2013 2014 2015

Co

nfo

rmit

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acto

r

Fu

el

eco

no

my (

MP

G)

Year

Real-world fuel economy NOx Conformity Factor

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Diesel MPG declining

30.0

35.0

40.0

45.0

50.0

55.0

60.0

65.0

2011 2012 2013 2014 2015

Fu

el

eco

no

my

(M

PG

)

Model Year of vehicle tested

Diesel - EQUA Mpg Diesel - official Petrol - EQUA Mpg Petrol - official

• Real-world average diesel MPG declining since 2012

• Official MPG kept rising until 2014, but even that now declining

• Petrol still showing gently improving trend

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Perils of downsizing

-45.0

-40.0

-35.0

-30.0

-25.0

-20.0

-15.0

-10.0

-5.0

0.0

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

EQ

UA

Mp

g v

aria

nce

to

off

icia

l M

PG

Engine size class (litres)

Diesel Petrol

• The smaller the engine, the bigger the gap between real-world and official MPG

• Sub-1.5 litre petrol engines have particularly large deficits

• NEDC rewards downsizing, but 1.5-2.0 litre optimal for mixed driving in reality

INDEPENDENT RATINGS

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• Vehicle rating scheme based on their real-world NOx emissions, launched in April 2016

• Non-statutory complement to new Real Driving Emissions regulations

• But will also

• Discriminate between high and low emitters, rather than just pass/fail

• Be updated for each model year to keep up with new calibrations

• Ratings are published and into the public domain for free

• Manufacturers and consumer media can adopt as independent, voluntary standard

• Similar to New Car Assessment Programme (Euro NCAP, Global NCAP)

Robust, independent standard needed to measure and incentivise actions to bring about air quality improvements

EQUA Air Quality Index

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www.equaindex.com

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Rating bands

Rating Lower bound

(g/km, exclusive)

Upper bound

(g/km, exclusive)

External reference point

A 0.00 0.08 Meets Euro 6 limit for diesels, and meets Euro 4 limit

for gasoline

B 0.08 0.12 Meets 1.5 Conformity Factor under Euro 6 Real

Driving Emissions regulation

C 0.12 0.18 Meets Euro 5 limit for diesels (and similar to 2.1

Conformity Factor under Euro 6 Real Driving

Emissions regulation)

D 0.18 0.25 Meets Euro 4 limit for diesels

E 0.25 0.50 Meets Euro 3 limit for diesels

F 0.50 0.75 No comparable Euro standard: roughly equal

to 6-8 times Euro 6 limit

G 0.75 1.00 Roughly equal to 8-12 times Euro 6 limit

H 1.00 None Roughly equal to 12+ times Euro 6 limit

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Diesels with A ratings

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Diesels with A ratings

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www.equaindex.com

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www.equaindex.com

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www.equaindex.com

• MPG values for almost all vehicles on sale in last five years

• Over 66,000 model variants

• Around 5,000 test values

• Remainder extrapolated using new proprietary model of real-world MPG, based on technical characteristics of vehicles

Comprehensive alternative to official system

Jane Thomas, Business Manager

jane@emissionsanalytics.com

+44 (0) 20 7193 0489

+44 (0) 7958 405409

www.emissionsanalytics.com

www.equaindex.com

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